SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6efd3a51c0edf43dc3a203fb08fefaf9227e9aa37576a397ba6ed0731839f389' 
  AND token = 'c2A9GxyFKfjnlDzYRzimacPYlkWCcGLLfniH4rmIxZc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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