SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d421d06d14be9fc33d9c75c2c68fb19f4daa892a35e9df9bb78a7b34d239f50' 
  AND token = 'iQvlE41WUaJrttCBYQNKa+HwqOmXFKjBMZ2c68Qb+9k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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