SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c671663580e00a46ffa54ebaf59063ee074935fa01680646200aab25255a54e6' 
  AND token = 'VTYJirh5x2kP8X+nErAsBMf214znKQP7MQh/y5WUKBk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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