SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0dd573f0578b96de8149d0fa11d06c85eb2f811d631cfc1b4723d28f54a49689' 
  AND token = 'Ava21dSrC2xxiPYe0ExcoHu0Gkl6SkFWj8edq7nQWzE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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