SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '956bf276c83db126fbb2f9c158ba798c3f54d2b0278133f7145e071731f51426' 
  AND token = 'FXyn+gKrLGAx7IhikS90wuPa3nVZbKVnxQmHuLiXT/w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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