SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b356f04ebdae9b3fd6ebf06fbf7053e8d36c64a83554423f5520d0d15490de3e' 
  AND token = 'UeUMPdRvSMguQgRd5TPUHGElQcWth11vZoc4oOv+pCc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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