SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3d8d3c70f75675a52b9c9a19dfd9f5610f584f7aeb5576e52bd5871d1eecebc' 
  AND token = 'KjYjuCGiWthrvTb+OURfBwAcLh33vgJ0GOaYwSNNo8w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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