SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a4d568d9cd43b0981675627e0a621e1d4f4893f6b13e712122fa57d31494585' 
  AND token = '9/JDTq/l4gNhMIHzA0aZW6nd3FsIWQeKwMaTdJwVvho=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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