SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fa40239f71666cb90c811ddb98d0b36ed5e33429e023cf2f1219f3380f1a688' 
  AND token = '673n9OMuXLpBVCpc796GaksNWif0SyjqzCVkKQY3eLY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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