SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f915312ee377db7b453761ac417e802c26eae3840d4e9fcddd0d51c7cfc8c7ea' 
  AND token = 'vwNBBRyEsG0dqJcd5jhIuqDt3eXUUQ+2cz//GPK8jQg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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