SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '577589f224168b45d35e97a06d3eab42df6e60e6cdd1e901990a3f3d356c0f9c' 
  AND token = 'xKYRHPiZvzqcdBL1UdwjowFjAeg4CDN+PCZ9HEqmXRA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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