SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6acfcae0715c285ba363373883553a99028eacbe456fde2e0ed214687da53b76' 
  AND token = 'Iy5mJWJtsHZirvRbVXduDqr3QSd4LPFdXlaHotBwWSE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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