SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bf35de0dbb34987e4050f4b1d8000825fb0672f59275882a1d5829defcbcd066' 
  AND token = 'rukFrB0FKNFaAZW4wJ+DU9u2ySkGM44CYclmKDzHXt4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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