SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d12ebff92130fd474521f7aa9d602e8e73a60e40df5e9574db755798a2d392b' 
  AND token = 'dSnQXTNlMVoL+UGqIeIuz+vaul6jJUNTHgiAHx4V6ZU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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