SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a33fb37b3235e78aae8269745ec17c705f1670e949bf7bfe6616025b9255d8ba' 
  AND token = '/j7aJNQZSaIV4gdD+IQHXalvTYNwPwQkbVzME5Yurv4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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