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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90345e3990c938679b204cd2224b5b21e5d1bd463c64e3d6a51061f382c83fb0' 
  AND token = '5GoKk8hIjpf8XS9+BExy7/PuXST1M+RjhsY961wkNNY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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