SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b38642a03a9f9f803cbf568bcf2190eed92f74db193609fc1dbfdcd992f6c9ee' 
  AND token = 'RtIpngwu9Wv5yjYdO+Crt2MYTOEZJqh56Qc/DzKp3RA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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