SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '231d106c34891ec208479d6f4e0b68ba2f39477a498294849cbf9d2829c497d3' 
  AND token = 'LZ+PzhbOXBYeY5JynK7GCLKZUVdwPyEV569TkJIRq7A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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