SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8ebac730605ef9f1ff26a7e588241793bf8c2cea3a4aa230d931954ef8edb34' 
  AND token = 'NcJIjE6NmtJmcnMTIaDliE44vKajcT6YiOJ1c4FhFfQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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