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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef6124b08cc67809a1ac0adbf1eb36a79983a8a60780c2a35aaf4207c5d1bb0f' 
  AND token = 'zIwRm1VGhH2tZZNrqPeUe9bZKVc19+CGOXBQFMT5ybQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}