SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '719e00706849b149feee50c9af389413b6d2a8ed4d13b649d1be4358eed287aa' 
  AND token = 'QdpKWVoWqq0iGmh4HyQBD1mdHhzOLSeMmZWSv/qbrp8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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