SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3d39708b20266664741efedc1acf19930513a058eead268ba28ec898e85d209' 
  AND token = 'AiR7EhfG0k+B5b4LAhMXsW/oaChk6aMj54olmEeEQKk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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