SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '00d8fe2ead565e050c80144fea6a5c518917e02e78749a22ef527d634d8e0fdc' 
  AND token = '++bhqZcYqRqhSMj6dUUrARasqYnK455w4w3MLhWTrg8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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