SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1627efa4825b712c05dd5b6440fbbee669716f5feef1d25bf49ad15b54a3d07' 
  AND token = 'BFswjRbKA8tmVWiudydV4l7dUvrqZAy6WRiZL2KZxLk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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