SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b36bd500c2fffdcb906add5f2376586c9bf5ca09ca86d4534e790cdf82b5ad4' 
  AND token = 'L6GUGAjIbOn9G0dKN1aPGyN4F7AsdyF6kkbeAynBMwI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}