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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9fc0376c344349353e54d0ab03966a631d4c4b4ec8029cdd74789dc955b85d53' 
  AND token = '+VFSz7vUDNfY0/vtjdguIUH7DkN/2p4ZddkTPQdHt/I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}