SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31019b0189c3474e27742d3fb94269754d57adaceea66595105158cb41494a10' 
  AND token = 'j0h9fCHJu5V6P5nsSniLHkk3PFUWYSlbqnQROmFZeAM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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