SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6794b9f304b004f3ae90125621e91d94bc59cc66afd27b2f2d5d9ebe236b60c3' 
  AND token = 'sOz3oaGNKwbMF+Ja+t05RY/eynWHrwSTCBARdweJmMU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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