SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66123a373644a41c9e7ecb2794758b914816e5cc9bedb27adb761c9f003d0aea' 
  AND token = '6dGsZjeRvxJZkKwWu0AWxE5tiIjW76CM5MNhtVDYJEE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}