SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98d53b97ff123ef127622e1d98ba84ba0e3c5f4eb0f7067fe8d4d988323942b7' 
  AND token = '/ktsykNSVIy9YshfMTnrdHF2BxlbBXgCnYvfnrGJUMI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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