SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ffef84d6591cfb536bdeb1b91afa2103dbbb716848befdfb94bb5fe5da4ae1a0' 
  AND token = 'c8CrVAvjLTXezXjNUXVVvrq1VdoN2Ug9vDW4nR/7GiQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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