SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2e9b754feab573e55a5b5fcf4f35f2cfa63727bcd82a611a1040242c53319f4' 
  AND token = 'zuARx9BS9lvsZyDQf+aUyhtRY3MUwJNXn8gPHYXz1+E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00008

JSON explain

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