SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a91ed5e2a89edd7d5ab079fcc92aaa6b418770cca1b43041ec8d6773892c8583' 
  AND token = 'a3ElgME6nNjE2g05jWF9TJJVfaZgPPCrYNaKhbzNzL8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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