SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe39c643260a8e689d1d65356b1348b7ab10cfb1d8b89f10952c237bd9de8e74' 
  AND token = 'HwFz2iTgk6AOZvIgZR5QgQZGfhHDuou7LdylQayce34=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

JSON explain

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