SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '135ef4c92cefe66bdefdfdb5766952673ae20697d932aa057b3c83f3c1f8a2ec' 
  AND token = 'T8wA3RBuHmWwmHPZHXp2GZ1n1uxr9eadlrCOEz3d+vw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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