SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd82a66792d29516907802f2509ac8f92caff0d1c9ddfa3465b11550e20cfbc4' 
  AND token = 'sLvtPhmPaMaY5YhqTnbTP5aZ/5mGP9FbriSxLZkMyiE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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