SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99c0650b2f6e963094e619dd7aaa2612c6086d27816c3f89559f80c559836823' 
  AND token = '8xDczPkolrWQGraVSEqvvXBML3e7T/9ZCPukD8BsTEI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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