SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '280d495d1331e6d755a3b5c950d547108462cbd5561d489e65f79a24f2835980' 
  AND token = '6hfwuAddKzXKb+OKqp2pBpVH6VnQOWQSnt1DmE/+Dtc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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