SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ce3ffd0ba5a188ad260f064c935cd36de7f259eaa4ae243fad66d01a791735ec' 
  AND token = 'kXO0qo/7tmvBWjIJZ6NdjF4fhmTV4CNFYbsH7OdxNm8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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