SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3efe4e32460aab3f73ef465c8e137504a4de00311fe7932197e016e39ade4e53' 
  AND token = 'FOfMzT2GynkhVzW1CRjwWaVdmwmDUrqQKuxLgbJwOOE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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