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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af6cd9fecec27a2733be1ea58feead554bceeb986ce3cc0e207dc32b33a3b89e' 
  AND token = 'UCeSdLJMPE4gkt6zNHaXb6tuCDK2Nxvj5iiHhdKfZMU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00009

JSON explain

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