SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8415e0d7a5c01b25fbbfc8ea197195b57402fcb2da78617586bfbde00761ee2' 
  AND token = 'PLVVdUyDNtKX38WTY2Uv0tOgFxGUULyMxaqynn01ui8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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