SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3186ba66dc7c459f5a75f62d45b0335dcd96d83c290c79cf54856c9b7cabc33' 
  AND token = 'GXEgV+GKr4QyxTiwv4ZgbbOJAMihl3Hd6v4UmDKvoXg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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