SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b99ab187c94f724f86a2af38301ef246126cf6aefa6d75285908b2b5801bed6' 
  AND token = 'WAVj+9RAR1m5GLDlFl+aE/lxGBpzBDcF081ph5NZS+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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