SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '868ce773f3f0c72fcc124175b1a4e22a128ed460cae3ca133c01da040555ab1f' 
  AND token = 'yazRolda5B2ByUMGVVqmpIOweA0ee74ixbrMoxKBWv4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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