SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a6a8347f390d9abad1a0e5ec9c2fa4a17a873d902f4c2a6cd05559b4843fa2f' 
  AND token = 'FE5CwvcOz5QPLGDUvy8EXDVFycBjmhAjThJcKrNNyRQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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