SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0e7b04fa0c1717b7b06342b5098b300d304f8bf372482dcdcc360897fd91694a' 
  AND token = 'y9+xBtF5IxtdQfXIags0jAiAUHdletnwdYDnYXqY6NA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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