SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71e81ac4dd8d3b501ecfefb52bb763490ce9a97de882493f2cdb866dab294cac' 
  AND token = 'HQYMpfzjDY25GJwOhsIlKNXnZmhaMz3HKlgatGKixRQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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