SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e7a895140f65ff0fe76b8564c92e454ef7e2da11ffd67fa750cf19c23f74543f' 
  AND token = 'XYqXVZYSJ16BVYimqZ4q2+RPXbHxAmrZ+JSQRB1GkBU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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