SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '736d99645d064851286dabdc2539ebdc2a3739eaecacdeca574f2fa5014f8fb9' 
  AND token = '5ZU+dWmPpvKLDpU1bA5s+oiQWF4KuYNbGkaH7UQQrYA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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