SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9251f8815cb9aa1c3d55a3f7eef43606d49f9671e79510fbc9d835ee3b4718bf' 
  AND token = 'YSIwATgc7vcwTsTpI+rIFhQDiPWLLnmVF5tNFEdQ0CI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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