SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8373e65058694dea7fd997013e3f74da3bb920e5c278806384b5244224a399ce' 
  AND token = 'tBtl/CqwVyPbnmLhkQvdG9TOKjnXz6K5HYWGevoE+cI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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