SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '709bc551b85cf07be50c0aad74d3442f677d9623bf025f6f851f6286a7a81026' 
  AND token = 'sZM2zHj6b9WKjEWTZBmASeZvgySqicRItwl3r+0Paug=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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