SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6db46d46592f628c7e85ad0aba1474b802f81abb7f71e1d119a52843d1480b83' 
  AND token = 'y9lUiTSq9ejZc1y3JDXq0YUhL2peoIwKWjMIJybMJCU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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