SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8310e46c51a438b2e3c756acca7ec97f4fd0e9f5a6551b4f664d3ab04d0e6de7' 
  AND token = 'SLiSraR52WE4SnfmDM3JjR0YXwb8/thLfwRjXXuQsq8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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