SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '777fd7027bcecf6bb388611709da99d396670caf2e1f4d46f8e86a835c0d779d' 
  AND token = 'g/Xyt3K94taZiBVA0mC2DMw1XrhoRBZpr4oTChinyh0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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