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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '86db9bf3fa0e5ae1fdc789c357b4c4987917258a8c5ee2fa42701fde3579c15a' 
  AND token = 'yzqxc2PqtyxCxdtsbcYF1CG3Oj+yCSCgT4b25FiOUZc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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