SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2d783e8394eada1c14711fda651869e4e98232b3239a49653d5d63abe492ce88' 
  AND token = '6s0QmRi5cjpCiIie1unwi7hswqqiUxg/HGzmK5JXTZY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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