SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a551437b417e919fae93190ca71a999120470f4579819b9cb62819773debcc54' 
  AND token = '479Uxx0oiZf9QrmmXw782nV+AHBQ7KXjTfNC2K+myLE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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