SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8386a932d95b444324e241b8d60df891e6366706334b719984b4d635f7abfaec' 
  AND token = 'qsrnBQ5Jch+Ep6AYLUx7ICTuuYPXCbQR+UDYdC+jbJo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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