SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad6a83d630e461beb2daac6efb793bcf996dea50ce53a67ac94d578da1e1b626' 
  AND token = 'DE9kXDBa0/jxzOFq83u7OM3YWJOG79ZxunGgrNyHFf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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