SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '678f44f728c0f474771d7c017ce2dcc14408c976594876ec59f232a2cb41427d' 
  AND token = 'Hlmwie5nJPCPiNWc/03QGEtIenMt2T8MPGmbeuEjDbQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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