SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f70bec785498362a5bba7fdcf12b54f3a7611aed69155f0daa50cc25c0cb5c02' 
  AND token = 'LfMSZNedenXC/jQhQ9BaZ7jJuNDZv+pIUmrgOqqpgmc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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