SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12e6f296fd674f45ed444b38cee0e028e8e64f2bb7612cd10de4256b267c8d3a' 
  AND token = 'BrGzag4ckOeTLbpm2CiJZjoFL4uKNRLRi+GdButiyw0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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