SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0ad4093c10f243bf294d15a013faf76d362ce401b764e585435645ad4d01165e' 
  AND token = 'mXX3hQ9tM80nDeuN+h6H0itNnXzRe5oXvEEHNVimriE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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