SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c28a655b88b63cda8cb5c94248937aea3320e080714698e72f1d046fcb760886' 
  AND token = 'mdOZt7rPeTzyziWPlH2+0hTS3VT0LSJP8CeIp2j94fk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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